Immunocytochemistry of four mixed pituitary adenomas and intrasellar gangliocytomas associated with different clinical syndromes: acromegaly, amenorrhea-galactorrhea, Cushing's disease and isolated tumoral syndrome

Mixed pituitary adenoma/pituitary neuroendocrine tumor-gangliocytoma: Immunohistochemical insights

Mixed pituitary adenoma/PitNET-gangliocytomas (PA/PitNET-GC) have been reported in small series over the past 20 years; some had limited immunohistochemistry (IHC) data. We interrogated our experience over 20 years, focusing on patterns of the GC component and IHC results for anterior pituitary hormones, transcription factors, NFP, and CAM5.2. A search of cases from 2002 to 2023 yielded 20 cases: 7M:13F, ages 20-71 years; 17 macroadenomas, 1 microadenoma, 2 ectopic. GC was co-associated with 4 corticotroph, 2 densely granulated lactotroph, 5 mixed lactotroph-somatotroph, 1 immature PIT1-lineage tumor, and 8 sparsely granulated GH; the latter all had a minor lactotroph component. Patterns were: discrete nodular foci of GC (9/20), extensive GC differentiation often overshadowing the PA/PitNET (7/20), and intimate admixture of smaller bands of neuropil and individual metaplastic ganglion cells within PA/PitNET (4/20). NFP highlighted small cohesive regions of neuropil and identified greater axonal content, including individual axons within "pure" PA/PitNET areas, than appreciated on H&E. CAM5.2 IHC often revealed cells with neuronal morphologies to a greater extent than NFP and in different areas within the same tumor. These data suggest that the combined use of NFP and CAM5.2 IHC best reveals transition from PA to GC phenotype, with CAM5.2 positivity reflecting earlier stages of transformation.

Case report: Clinical and single-cell transcriptome sequencing analysis of a mixed gangliocytoma-adenoma presenting as acromegaly

Background

Mixed gangliocytoma-adenoma (MGA) is a rare tumor of pituitary gland. It's difficult to distinguish it from pituitary adenoma by clinical manifestations, imaging features or serological testing. Thus, the histopathological examination is still the golden standard for diagnosis. Besides, studies on molecular level are still lacking.

Case information

In this case report, we described a 28-year-old male with MGA presenting as acromegaly, who suffered staging operation and post-operation gamma knife radiosurgery, but finally died of secondary hyperglycemic hyperosmolar collapse. A complete data including clinical, histopathological, ultrastructural and single-cell transcriptome level information were collected and analyzed.

Conclusion

This case report detailed the only clinical and molecular report of MGA following operation and radiotherapy. Complete clinical data enhanced the understanding of the diagnosis and treatment of this disease. Besides, the single-cell transcriptome sequencing analysis further disclosed the intra-tumoral heterogeneity and provided support for subsequent basic research.

Mixed gangliocytoma-pituitary adenoma in MEN1 syndrome: A case report and literature review

Pituitary adenoma is one of the three most common neoplasms described in multiple endocrine neoplasia type 1 (MEN1), and patients with pituitary adenoma occupies 30-50% of those with MEN1-related tumor. Mixed gangliocytoma-pituitary adenoma (MGPA) is a rare clinical entity in which gangliomatous cells are intermixed with adenomatous cells. This tumor has been estimated to account for 0.52-1.26% of all pituitary tumors. We report a rare case of MGPA in a patient with MEN1. A retrospective chart review was conducted on a patient with MEN1 diagnosed with MGPA in 2019 at a single tertiary academic medical center. A review of the literature was performed on MGPA and pituitary adenoma in MEN1. MGPA is rare, with only 174 cases previously reported in the literature and only three prior case reported in a patient with MEN1. There are multiple hypotheses regarding their pathogenesis, and it is unclear whether the MEN1 gene (menin) plays a role in the pathogenesis of MGPA. This tumor in MEN1 is a rare clinical entity of unknown etiology. Further studies are required with difficulty due to its low incidence.

Observation of Clinicopathologic Features of Pituitary Adenoma With Neuronal Differentiation

OBJECTIVE

To investigate the clinicopathologic features of pituitary adenoma with neuronal differentiation.

METHODS

Four patients with mixed gangliocytoma-pituitary adenomas between January 2011 and January 2021 and 111 new-onset patients with adenomas between January 2019 and June 2021 who attended the First Affiliated Hospital of Fujian Medical University were included in the study. The histological and immunohistochemical findings were analyzed. Neuronal differentiation marker staining was performed on new-onset adenomas, and the related literature was reviewed.

RESULTS

Altogether, more than 100 mixed gangliocytoma-pituitary adenoma cases have been reported in the literature until now, of which pituitary-specific POU-class homeodomain transcription 1 (PIT1) positive adenomas are more frequently observed. In the present study, all 4 patients we described were female, aged 29 to 53 years (mean 39 years). Clinically, 3/4 patients presented with acromegaly, and 1/2 patients presented with headache. Histologically, the tumor was composed of two distinct mixed components. The one was a population of neoplastic ganglionic cells with large nuclei, prominent nucleoli, and abundant basophilic cytoplasm embedded in a fibrillary background. Stains of chromograninA (CgA), synaptophysin (Syn), Calretinin (CR) were positive. Axotomy-like expression was observed in neurofilament (NF) staining. PIT1 was expressed in partial ganglionic cells in all cases. The other component was a population of small uniform cells with round nuclei and acidophilic cytoplasm. Prolactin (PRL) and growth hormone (GH) were positive in all 4 cases. PIT1 was positive in the nuclei of adenomas. Although adenomas and ganglionic regions varied in histology, there was a population of cells with neuronal differentiation expressing PIT1. Additionally, axotomy-like expression of NF staining could be seen in a distant area of adenoma regions. A total of 111 cases of adenomas without ganglionic cells were included in this study, including 7 cases with neuronal differentiation. Among them, 4 cases were prolactinomas, 2 cases were somatotroph adenomas, and 1 case was corticotroph adenoma. 6/7 cases were PIT1-positive adenomas. And the remaining one case is T-PIT-positive adenoma.

CONCLUSIONS

Mixed gangliocytoma-pituitary adenomas are rare tumors with neuronal differentiation. The majority of MGAs are associated with endocrinopathies, mainly acromegaly. Our results suggest that PIT1-positive pituitary adenomas may have neural differentiation potential, which may not be unusual. This indication supports the possibility that the neuronal transdifferentiation of adenomatous cells is a possible mechanism, and the underlying mechanism requires further elucidation.

Acromegaly Caused by Ectopic Growth Hormone Releasing Hormone Secretion: A Review

INTRODUCTION

Ectopic acromegaly is a rare condition caused most frequently by growth hormone releasing hormone (GHRH) secretion from neuroendocrine tumors. The diagnosis is often difficult to establish as its main symptoms do not differ from those of acromegaly of pituitary origin.

OBJECTIVES

To determine most common clinical features and diagnostic challenges in ectopic acromegaly.

PATIENTS AND METHODS

A search for ectopic acromegaly cases available in literature was performed using PubMed, Cochrane, and MEDline database. In this article, 127 cases of ectopic acromegaly described after GHRH isolation in 1982 are comprehensively reviewed, along with a summary of current state of knowledge on its clinical features, diagnostic methods, and treatment modalities. The most important data were compiled and compared in the tables.

RESULTS

Neuroendocrine tumors were confirmed in 119 out of 121 patients with histopathological evaluation, mostly of lung and pancreatic origin. Clinical manifestation comprise symptoms associated with pituitary hyperplasia, such as headache or visual field disturbances, as well as typical signs of acromegaly. Other endocrinopathies may also be present depending on the tumor type. Definitive diagnosis of ectopic acromegaly requires confirmation of GHRH secretion from a tumor using either histopathological methods or GHRH plasma concentration assessment. Hormonal evaluation was available for 84 patients (66%) and histopathological confirmation for 99 cases (78%). Complete tumor resection was the main treatment method for most patients as it is a treatment of choice due to its highest effectiveness. When not feasible, somatostatin receptor ligands (SRL) therapy is the preferred treatment option. Prognosis is relatively favorable for neuroendocrine GHRH-secreting tumors with high survival rate.

CONCLUSION

Although ectopic acromegaly remains a rare disease, one should be aware of it as a possible differential diagnosis in patients presenting with additional symptoms or those not responding to classic treatment of acromegaly.

Sellar Gangliocytoma: Case Report and Review of an Extremely Rare Tumour

Sellar gangliocytomas (SGs) are rare, well-differentiated, low-grade neoplasias that commonly present along with a pituitary adenoma (PA). We describe a case of a 52-year-old woman with a 2-year history of headache, body weight increase, and recent onset of arterial hypertension and type 2 diabetes mellitus. Work-up tests revealed a normal hypophyseal profile, except for mild ACTH elevation, and a sellar mass on magnetic resonance imaging (MRI). A diagnosis of an enlarging pituitary macroadenoma was established, and to prevent symptom progression, the tumour was resected. Pathology showed 2 cell populations: ganglion and corticotrope cells. Three years after surgery, the patient no longer had a headache but persisted with arterial hypertension and type 2 diabetes mellitus. A literature review produced 207 cases of SGs. They typically present in women at 40 years of age and the most common clinical presentation are symptoms of acromegaly. Of the documented cases, 74 and 93% were treated with surgery alone or combined treatments (radiotherapy, radiosurgery, or pharmacotherapy), respectively. The majority of deaths associated with a SG came from the first half of the 20th century. In conclusion, this patient presented with a silent SG with likely pituitary hyperplasia. SGs are a challenging diagnosis, have a benign course, and may provide insights into PA tumourigenesis.

Hypothalamic hormone-producing tumors

The hypothalamus is functional neuroendocrine tissue that is responsible for the synthesis and secretion of peptide hormones that regulate the pituitary and other endocrine functions. Endocrine tumors of the hypothalamus are rare but they provide a model for tumors that have both structural and functional effects. Patients with hypothalamic endocrine tumors suffer mass effects including headaches, visual disturbances, and endocrine dysfunction due to structural damage to hypothalamic nuclei, which regulate appetite, temperature, diurnal rhythms and emotions. In addition, these tumors can secrete hormones that can cause acromegaly, Cushing disease, hyperprolactinemia, and the syndrome of inappropriate antidiuresis. Morphologic classification of these tumors has provided evidence for two classes of tumors, gangliocytomas that are composed of large neurons and neurocytomas that are comprised of small cells; these resemble the variants of magnocellular and parvocellular neurons in the hypothalamic nuclei. Biomarkers are used to classify these tumors and achieve accurate structure-function correlations. While surgery remains the mainstay of therapy, novel medical and radiopharmaceutical approaches are available for patients with progressive and/or unresectable tumors.

[Primary sellar neuroblastoma (clinical case and literature review)]

Neuroblastoma is a malignancy developing from the embryonic neuroblasts of sympathetic nervous system. Primary sellar neuroblastomas are extremely rare (there are currently only 11 case reports in the literature). Possible development of neuroblastoma in sellar region expands differential diagnosis of local processes due to inclusion of neuroblastoma into the spectrum of suspected tumors. We report a literature review and description of a patient with primary sellar neuroblastoma.

Hypothalamic Endocrine Tumors: An Update

The hypothalamus is the site of synthesis and secretion of a number of endocrine peptides that are involved in the regulation of hormonal activity of the pituitary and other endocrine targets. Tumors of the hypothalamus have been recognized to have both structural and functional effects including hormone hypersecretion. The classification of these tumors has advanced over the last few years, and biomarkers are now available to classify these tumors and provide accurate structure-function correlations. This review provides an overview of tumors in this region that is critical to metabolic homeostasis with a focus on advances in the diagnosis of gangliocytomas, neurocytomas, and pituicytomas that are unique to this region.

Mixed gangliocytoma-pituitary adenoma containing GH and GHRH co-secreting adenoma cells

SUMMARY

A 67-year-old woman with a past history of type 2 diabetes mellitus presented with worsening glycemic control. She had some acromegaly symptoms and magnetic resonance imaging demonstrated a pituitary tumor. Endocrinological examination found the resting growth hormone (GH) level within the normal range, but elevated insulin-like growth factor 1 level. A 75 g oral glucose tolerance test showed inadequate suppression of nadir GH levels. Acromegaly due to GH-secreting pituitary tumor was diagnosed. The patient underwent endoscopic transsphenoidal surgery resulting in gross total removal of the tumor and recovered well postoperatively. Histological examination of the tumor showed coexistence of relatively large gangliocytoma cells and pituitary adenoma cells, suggesting mixed gangliocytoma-pituitary adenoma. In addition, colocalization of GH and GH-releasing hormone (GHRH) in pituitary adenoma cells was revealed, so the adenomatous components were more likely to produce GHRH in our mixed gangliocytoma-pituitary adenoma case. Mixed gangliocytoma-pituitary adenoma is very rare, and the present unique case demonstrated only the adenomatous components associated with GHRH production.

LEARNING POINTS

Sellar gangliocytoma coexisting with pituitary adenoma is recognized as a mixed gangliocytoma-pituitary adenoma and is very rare. A proposed developmental mechanism of growth hormone (GH)-secreting mixed gangliocytoma-pituitary adenoma involves GH-releasing hormone (GHRH) produced by the gangliocytic components promoting the growth of tumor including GH-secreting adenomatous components. Since our present case indicated that the adenomatous components of mixed gangliocytoma-pituitary adenoma could secrete both GH and GHRH simultaneously, progression of GH-secreting mixed gangliocytoma and pituitary adenoma may involve exposure to spontaneously produced GHRH due to the adenomatous components.

Mixed gangliocytoma-pituitary adenoma in the sellar region: a large-scale single-center experience

BACKGROUND

Mixed gangliocytoma-pituitary adenoma is an extremely rare tumor occurring in the sellar region, histologically composed of both gangliocytic and pituitary adenomatous architectures. The histogenesis of these tumors remains unknown, and the diagnosis, treatment, and prognosis are yet to be fully understood.

METHODS

We retrospectively reviewed the clinical, radiological, and histopathological profiles from a series of 20 patients with sellar mixed gangliocytoma-pituitary adenomas. All patients underwent surgical tumorectomy via an endoscopic or microscopic transsphenoidal approach. Perioperative magnetic resonance imaging (MRI) and computed tomography (CT) data were reviewed. Immunohistochemical stains and electron microscopy examination were performed. Follow-up outcomes were presented.

RESULTS

This case series consisted of 13 females and seven males (age range, 20-59 years; mean age, 42.3 ± 11.2 years). Preoperative endocrine examination showed elevated growth hormone (GH) in nine patients and hyperprolactinemia in eight patients. The tumors were positive for GH in 15 cases, prolactin in 13 cases, adrenocorticotropic hormone in three cases, and thyroid-stimulating hormone in one case. Gross total resection was achieved in 15 patients, and subtotal resection in five patients. During an average follow-up period of 42.5 ± 29.0 months, no recurrence was noted.

CONCLUSIONS

The clinical and neuroimaging features of sellar mixed gangliocytoma-pituitary adenomas are non-specific, and invasion into the cavernous sinus is common. Surgical resection via a transsphenoidal approach is the preferred treatment, and the surgical outcomes are favorable. Moreover, our histopathological findings are more likely to support the theory that mixed gangliocytoma-pituitary adenoma originates from the neuronal transdifferentiation of adenomatous cells.

Transsphenoidal Surgery for Mixed Pituitary Gangliocytoma-Adenomas

BACKGROUND

Most sellar gangliocytomas are discovered with a concurrent pituitary adenoma, also known as a mixed gangliocytoma-adenoma (MGA). MGAs are rare, with fewer than 100 cases reported in the literature to date and only 1 previously documented surgical series. Because MGAs are radiologically indistinguishable from pituitary adenomas, they are often diagnosed after surgery. Combined with the paucity of clinical outcome data for these tumors, this makes their diagnosis and management challenging. Here we describe the clinical presentation and outcomes of 10 individuals who were diagnosed with a MGA at a single institution.

METHODS

This retrospective case series study included patients diagnosed with a combined sellar MGA between 1993 and 2016.

RESULTS

This series comprised 10 patients, mean age of 44 years (range, 28-63 years) diagnosed with an MGA. The mean tumor size was 1.6 cm (range, 0.4-2.4 cm). Five patients presented with acromegaly, and 1 patient had recurrent Cushing disease. Transsphenoidal surgery was performed in all cases, and gross total resection was achieved in 7 patients (70%). Histologically, 9 of the 10 MGAs were identified as mixed somatotroph adenoma-gangliocytomas. The median duration of follow-up was 74 months (range, 2-180 months). Following adjuvant treatment (n = 3), all patients with acromegaly (n = 4) achieved biochemical remission, and no patient experienced recurrence of the pituitary tumor with a median radiographic follow-up of 48 months.

CONCLUSIONS

MGAs are often associated with a hypersecretory adenoma. Transsphenoidal surgery is well tolerated by most patients, and when performed in combination with adjuvant therapy, a low rate of recurrence and reversal of preoperative endocrinopathy can be expected.

Anterior Gray Matter Pituicytic Heterotopia with Monomorphic Anterior Pituitary Cells: A Variant of Nonsecretory Pituitary Adenoma Neuronal Choristoma? Report of a Rare Case and Review of the Literature

BACKGROUND

Mixed tumors of adenomatous and neuronal cells in the sellar region are an uncommon finding. The origins of these heterogeneous tumors are unknown, and management remains unsettled. We report a very rare case of anterior gray matter pituicytic heterotopia with monomorphic anterior pituitary cells that likely represents a variant of nonsecreting pituitary adenoma neuronal choristoma (PANCH) with no ganglion cells. We also review the current literature for the various clinical presentations of PANCH.

CASE DESCRIPTION

A 49-year-old female complaining of headache, blurred vision, and hair loss was found to have a nonsecretory sellar mass with compression of the optic chiasm on magnetic resonance imaging (MRI). The mass was excised via a transsphenoidal procedure. Histological analysis of tissue sections revealed heterotopic gray matter with reactive gliosis without ganglion cells or Herring bodies. Only 1 smear exhibited characteristics of a pituitary adenoma.

CONCLUSIONS

The overall findings were most consistent with a variant of PANCH. At a postoperative follow-up of 4.5 years, there was resolution of visual symptoms, and the residual sellar mass was stable on MRI. Neuronal choristoma is hypothesized to originate from embryonal pituitary or hypothalamus, or by differentiation from pituitary adenoma cells. Surgery is the cornerstone of management, and the clinical course appears to be similar to that of nonfunctioning pituitary adenoma in reported cases.

Mixed Pituitary Gangliocytoma and Prolactinoma Resistant to the Cabergoline Treatment

BACKGROUND

A gangliocytoma rarely coexists with a pituitary adenoma in a sellar lesion. Herein, we describe our experience in treating a mixed gangliocytoma and prolactinoma of the pituitary gland.

CASE DESCRIPTION

A 16-year-old male presented with severe headache and vomiting. Magnetic resonance imaging showed a large pituitary tumor with hydrocephalus. Because of the increased levels of serum prolactin (PRL), we treated the patient with cabergoline, which decreased the tumor size and improved the hydrocephalus. Six months after the treatment, the tumor began to increase in size, despite the normalization of the PRL level with cabergoline treatment. An endoscopic transsphenoidal resection was performed and the tumor was mostly removed. Microscopic examination of the resected tumor showed a mixture of prototypical pituitary adenoma cells and the proliferation of mature ganglion cells. Immunohistochemistry showed that the ganglion cells were positively stained for synaptophysin, NeuN, and PRL as shown in the adenomatous component. A few cells were immunostained with both PRL and NeuN, and a few cells were immunopositive for nestin, but not PRL or synaptophysin.

CONCLUSIONS

Our findings showed the existence of cells that are phenotypically intermediate between ganglion cells and adenoma cells, and the existence of stem cell-like cells, which support the hypothesis that adenoma cells can transform into ganglion cells or that both ganglion and adenoma cells derive from common stem cells. Furthermore, the ganglion cells seemed to grow rapidly and independently of dopamine, which is in contrast to prototypical prolactinoma cells.

Characteristics of ganglion cells in pituitary gangliocytomas

The occurrence of ganglion cells in the sella turcica, in association or not with a pituitary adenoma, has been rarely reported. Various names have been employed for this rare entity, gangliocytoma being frequently used and recommended by WHO classification. Expression of cytokeratin in these ganglion cells has been previously occasionally reported, a very intriguing observation raising questions on the possible nature and derivation of these cells. We describe the pathological findings in three cases of growth hormone-producing adenomas, all sparsely granulated, showing the presence of a ganglion cell population admixed with an adenomatous component. A review of the literature is also provided.

Infrasellar pituitary gangliocytoma causing Cushing's syndrome

INTRODUCTION

Pituitary gangliocytomas are uncommon neuronal tumours that may present with endocrine disorders, the most frequent being acromegaly caused by growth hormone hypersecretion. Cushing's syndrome is very rarely seen with gangliocytomas.

MATERIAL AND METHODS

We report the unique case of a 62 year-old woman whose clinical picture and endocrine testing clearly demonstrated adrenocorticotropin (ACTH)-dependent Cushing's syndrome. Pituitary magnetic resonance imaging showed a 12-mm homogeneous, infra- and retrosellar mass first diagnosed as pituitary macroadenoma. Transsphenoidal surgery was performed and allowed complete resection of the tumour with sparing of normal anterior pituitary. Very low postoperative serum cortisol and ACTH levels were observed in the early postoperative period and the patient is still in remission 18 months after surgery, thus demonstrating that the resected lesion was entirely responsible for the clinical picture.

RESULTS

Histological and immunocytochemical analyses demonstrated a benign tumour composed of mature neuronal cells suggestive of a gangliocytoma, expressing both ACTH and corticotropin-releasing hormone (CRH). The tumour was surrounded by a rim of pituitary tissue containing ACTH-producing endocrine cells. Careful analysis of the resected lesion did not reveal any pituitary microadenoma. We search literature for similar cases and retraced only nine cases of gangliocytomas associated with Cushing's syndrome. In most of them, the tumour was combined with either pituitary corticotroph adenoma or hyperplasia.

CONCLUSIONS

Our case represents a unique case of an infrasellar pituitary gangliocytoma which was able to cause Cushing's syndrome by both direct ACTH production and CRH-induced stimulation of neighbour normal corticotroph cells.

Growth hormone-producing pituitary adenoma regrowing as pituitary adenoma with neuronal choristoma 14 years after tumor removal

BACKGROUND

We report a case of an uncommon association of pituitary adenoma with neuronal choristoma that usually is diagnosed at initial surgery.

CASE DESCRIPTION

A 50-year-old woman with acromegaly and bitemporal hemianopsia underwent removal of a pituitary adenoma via the transsphenoidal approach. Histologic examination of the first surgical specimen demonstrated only adenoma, which was eosinophilic and expressed growth hormone. Fourteen years later, bitemporal hemianopsia recurred, and magnetic resonance imaging revealed regrowth of the residual tumor.

DISCUSSION

The patient underwent removal of the regrown tumor via the transsphenoidal approach. Histologic examination of the second surgical specimen revealed gangliocytoma and a small component of pituitary adenoma.

CONCLUSIONS

The present case report supports the theory that pituitary adenoma with neuronal choristoma might represent the result of neuronal differentiation from pituitary adenoma.

Ganglioglioma of the neurohypophysis

The normal infundibulum and neurohypophysis consist entirely of neuronal processes, the neuronal cell bodies of which lie within the supraoptic and paraventricular nuclei of the hypothalamus and supportive glial cells or pituicytes. The finding of neurons within the neurohypophysis is exceedingly rare, as are ganglion cell tumors at this site. In this paper, we report a ganglion cell tumor of the neurohypophysis found incidentally at autopsy. Despite chronic hypertension and the finding of some vasopressin immunoreactivity in lesional neurons, the syndrome of inappropriate antidiuretic hormone secretion (SIADH) was excluded on the basis of normal serum sodium levels. The morphologic and immunohistochemical features of the tumor are presented, cytogenetic considerations are discussed, and literature regarding neuronal lesions of the pituitary gland is reviewed.

Combined gangliocytoma and prolactinoma of the pituitary gland

Gangliocytomas of the pituitary gland are rare lesions that often occur in combination with pituitary adenomas, which are frequently associated with the hypersecretion of pituitary hormones, particularly growth hormones. We report a case of combined gangliocytoma and prolactinoma of the pituitary gland. A 49-year-old male presented with vertigo. Radiological examination revealed an intrasellar tumor with a suprasellar extension, which was removed via the trans-sphenoidal approach. Histologically, the tumor was composed of adenoma cells, mature ganglion cells and cells with features intermediate between those of adenoma cells and ganglion cells (intermediate cells). Immunohistochemical analysis revealed the ganglion cells and intermediate cells as well as adenoma cells to be positive for prolactin. No growth hormone-positive tumor cells were observed. The ganglion cells were positive for synaptophysin and neurofilament. The findings in this case are discussed in relation to hypotheses proposed for histogenesis, and the presence of intermediate cells supports three hypotheses. The first is that adenoma cells transform into ganglion cells, and the second is that both components originate from the embryonal pituitary cell rests, showing intermediate features between ganglion cells and adenoma cells. The last is that their common origin may be the same stem/progenitor cells in normal adult pituitaries.

An unusual association of a sellar gangliocytoma with a prolactinoma

The simultaneous occurrence of a hypothalamic and sellar gangliocytoma with a pituitary prolactinoma is very rare. The explanation for such an association is not known. We describe the case of a woman who had a coexisting adjacent pituitary prolactinoma and gangliocytoma within the same sellar mass. The tumor cells of the gangliocytoma demonstrated expression of enkephalin, a product of proopiomelanocortin known to be a prolactin secretagogue. We postulate that in this patient there may be a link between gangliocytoma enkephalin and prolactin hypersecretion.

Ganglion cell containing pituitary adenomas: signs of neuronal differentiation in adenoma cells

Ganglion cell containing pituitary adenomas are rare. They represent tumors originating in the sella turcica which are composed of adenomatous and neuronal components. Recently accumulated information suggests a common origin for their neuronal and pituitary constituents. The objective of this study was to report the clinical and morphologic findings of pituitary gangliocytomas and study their immunoprofile using neuronal markers. Seven cases of pituitary gangliocytomas retrieved from 1,322 sellar lesions were studied. All tumors were removed from patients with mild acromegaly. Histologically they were biphasic composed of pituitary adenoma and clusters of ganglion cells embedded in a variably dense neuropil substrate. All adenomas belonged to the category of sparsely granulated somatotroph adenoma and were positive for growth hormone, whereas in five tumors, a few adenoma cells were also positive for prolactin. Ganglion cells were immunoreactive for NSE, synaptophysin and neurofilament protein (NFP). NFP-reactive fibrils were observed in the neuropil substrate and varied in number among the cases. Interestingly, all tumors contained varying numbers of adenoma cells with NFP-positive, dot-like areas of cytoplasmic reactivity, mostly tiny paranuclear, a finding not previously reported in human pituitary gangliocytomas. The presence of NFP in pituitary adenomas indicates neuronal differentiation in adenoma cells, suggesting a common origin for neuronal and pituitary adenoma cell elements in gangliocytomas.

Sellar neuroblastoma mimicking pituitary adenoma

OBJECTIVE AND IMPORTANCE

Primary intracranial neuroblastomas are rare. They generally arise in the supratentorial parenchyma or paraventricular region. Even more rare are primary sellar neuroblastomas. We present a neuroblastoma that arose in the sellar region and mimicked a non-functioning pituitary adenoma.

CLINICAL PRESENTATION

This 33-year-old man presented with bitemporal hemianopsia. MRI showed a sellar mass with suprasellar extension mimicking a pituitary adenoma.

INTERVENTION

Because of tumor recurrence and dissemination to the cervical region, he underwent 6 operations and radiosurgery. Detailed histologic examination confirmed the diagnosis of neuroblastoma. Postoperative conventional radiotherapy was effective in reducing the size of the tumor.

CONCLUSION

Neuroblastoma should be considered in the differential diagnosis of patients with sellar lesions.

Combined sellar fibrosarcoma and prolactinoma with neuronal metaplasia: report of a case unassociated with radiotherapy

We report the occurrence of a primary pituitary fibrosarcoma causally unrelated to radiotherapy, admixed in association with a prolactin cell pituitary adenoma showing neuronal metaplasia. These unique findings were associated with multiple endocrine neoplasia type 1 (MEN 1). Primary fibrosarcoma involving the sella is a very rare tumor. The majority of cases have been associated with prior irradiation of either a pituitary adenoma or a craniopharyngioma. Pituitary adenoma with neuronal metaplasia is also rare and usually occurs in the setting of acromegaly. Despite the intimate association of both elements in our lesion, no transition of adenoma to sarcoma was demonstrable by immunohistochemistry or in situ hybridization studies.

'Gangliocytomas' of the pituitary: a heterogeneous group of lesions with differing histogenesis

Hamartomatous or neoplastic ganglion cells in the sella turcica are an unusual cause of symptoms. They have been reported in association with a functioning or nonfunctioning pituitary adenoma, with pituitary cell hyperplasia, and occasionally as masses unassociated with an adenoma, again with variable endocrinologic findings. Fewer than 50 cases of intrasellar ganglion cell lesions have been reported in the literature, only six of them associated with Cushing's syndrome. We describe the clinicopathologic features of another eight patients, three of whom presented with acromegaly, four with apparently nonfunctioning adenohypophyseal masses, and one with Cushing's syndrome. On histology, six of them were found to have sparsely granulated growth hormone (GH)-producing adenomas with ganglion cell areas, one appeared to have a gangliocytoma not associated with an adenoma, whereas the eighth had a ganglion cell lesion in the posterior pituitary. The morphologic and immunohistochemical findings suggest that the ganglion cell component of seven of these tumors has resulted from neuronal differentiation in a GH-producing adenoma, despite the lack of demonstrable adenoma in one case. A true sellar "gangliocytoma" or hamartoma of ectopic hypothalamic-type neurons appears to be a rarer explanation for the presence of ganglion cells in a pituitary biopsy.

Gangliocytoma masquerading as a prolactinoma. Case report

The authors describe the case of a 36-year-old man who presented with bitemporal hemianopsia and a serum prolactin concentration of 1440 ng/ml. Magnetic resonance imaging of the pituitary revealed a presumed macroadenoma with suprasellar and temporal lobe extension. Although the patient's prolactin level was lowered to 55 ng/ml by bromocriptine therapy, no tumor shrinkage occurred. Fourteen months later, progression of visual field defects necessitated transsphenoidal resection, which was incomplete. Immunocytochemical analysis of the biopsy tissue was positive for prolactin and, in view of the clinical picture, more detailed analysis was not performed. External-beam radiotherapy was given 2 years later because of enlargement of residual tumor. Subsequently, despite a fall in the serum prolactin concentration to less than 20 ng/ml in response to the course of bromocriptine, the mass displayed further extension into the temporal lobe. Nine years after the patient's initial presentation, he underwent transfrontal craniotomy for sudden deterioration in visual acuity caused by hemorrhage into the mass. No adenohypophyseal tissue was identified in the resected tissue. The mass was composed of dysplastic neurons that were strongly immunoreactive for synaptophysin and neurofilament (indicating neural differentiation) and prolactin. Review of the original biopsy specimen indicated that the prolactin-positive cells had striking neuronal morphological characteristics. The final diagnosis in this case is prolactin-secreting gangliocytoma. Although exceedingly rare, this disease must be added to the differential diagnosis in cases of "prolactinoma" when bromocriptine therapy is followed by a marked decline in serum prolactin that is not accompanied by significant tumor shrinkage. Furthermore, in such instances, consideration should be given to "obtaining a biopsy sample prior to electing for radiotherapy.

Pituitary adenoma with neuronal choristoma: a report of two rare cases

Two rare cases of pituitary adenoma with neuronal choristoma are described. Both patients were female and presented with features of acromegaly with elevated growth hormone and prolactin levels. Radiologically, both lesions were predominantly intrasellar in location with extension into suprasellar region, but hypothalamus was not involved. Histopathological examination revealed a mixture of chromophobe pituitary adenoma cells and neuronal cells. In both cases, the adenoma component was positive for growth hormone and prolactin. Interestingly, immunopositivity for alpha-subunit, cytokeratin and prolactin was seen in the adenoma and neuronal cells in one case. Our findings support the hypothesis that the neuronal cells possibly arise from adenoma cells as a result of metaplasia.

Prolactin-producing pituitary adenoma and carcinoma with neuronal components--a metaplastic lesion

Recent studies indicate that cells of various epithelial tumors are capable of transformation to neurons. Observing both neurons and neuropil in two prolactin-producing adenohypophyseal tumors, one benign and one malignant, we sought to assess their cellular differentiation, the presence of nerve growth factor receptor, and expression of the dopamine receptor gene using immunocytochemistry, electron microscopy, and in situ hybridization. Light and electron microscopy clearly revealed cells morphologically transitional between adenoma/carcinoma cells and neurons. Large neurons lacked proliferative activity. Neurons in varying number showed immunoreactivity for pituitary hormones including prolactin, growth hormone and alpha subunit in the adenoma and prolactin alone in the carcinoma. The distribution of nerve growth factor receptor staining was similar. In both tumors, in situ hybridization showed mRNAs for prolactin and dopamine receptor within adenohypophyseal cells and neurons. Our results indicate that the occurrence of neurons and neuropil in growth hormone and prolactin-producing pituitary tumors appears to be the result of metaplasia. The process is not limited to benign tumors and may be due to the production of tropic substances by the adenohypophysial cells, which by paracrine/autocrine mechanisms result in transformation of adenoma cells to nerve cells.

GH and PRL-Producing Pituitary Adenoma with Neuron-Like Differentiation

A pituitary adenoma with neuron-like differentiation in the sella turcica is reported. Sections of the tumor showed a mixture of adenoma cells, ganglionic cells, and neuropil-like structures by light microscopy. Both pituitary adenoma cells and large cells recognized as ganglionic cells by H&E were strongly immunoreactive for both growth hormone (GH) and prolactin (PRL), which indicated that these large cells had properties similar to those of pituitary adenoma cells. Furthermore, electron microscopy (EM) revealed characteristic low electron-dense secretory granules as well as GH-type large electron-dense secretory granules in adenoma cells, neuropils, and swollen bulbs of neuronal endings, which indicated that these three populations may be of the same origin. Furthermore, we could not find typical cell bodies of ganglionic cells by EM. These results are consistent with a hypothesis that attempts to explain the origin of the neuronal components by the neuronal differentiation of adenoma cells. Thus, the best designation of our tumor may be "pituitary adenoma with neuron-like differentiation."

Intrasellar pituitary gangliocyto-adenoma presenting with acromegaly: case report

OBJECTIVE AND IMPORTANCE

A gangliocytoma in the sellar region is extremely rare. We describe a rare case of intraseller gangliocytoma coexisting with a growth hormone-producing pituitary adenoma, which presented with acromegaly.

CLINICAL PRESENTATION AND INTERVENTION

A 64-year-old woman was admitted to our hospital with headache and acromegaly. Endocrinological studies revealed an elevated serum level of growth hormone (GH). Magnetic resonance imaging showed a tumor at the intrasellar and suprasellar regions. The tumor was totally removed via a transsphenoidal approach.

RESULTS

A histological examination of the resected specimen showed areas of ganglionic cells and adenomatous cells. Immunohistochemical examination demonstrated GH-releasing hormone-positive ganglionic cells and GH-positive pituitary adenoma.

CONCLUSION

Based on these immunohistochemical findings, we hypothesized that the intrasellar gangliocytoma promoted the growth of the pituitary adenoma, which had been transformed from a region of pituitary hyperplasia by chronic overstimulation from excess GH-releasing hormone produced by the intrasellar gangliocytoma.

Differentiating neuroblastoma of pituitary gland: neuroblastic transformation of epithelial adenoma cells. Case report

The authors report the case of a 40-year-old woman with a 12-year history of irregular menses, amenorrhea, infertility, galactorrhea, a slightly elevated prolactin level, and a slowly growing pituitary adenoma. She developed recent onset of visual symptoms, prompting craniotomy for removal of an intrasellar tumor. Following surgery, her vision and prolactin levels returned to normal. Light microscopic and immunohistochemical examination of the tumor revealed it to be a neuroblastoma, which was immunohistochemically positive for synaptophysin, S-100 protein, and oxytocin. The neoplasm contained prolactin-positive neuroblastic and pituitary epithelial cells. No other pituitary hormones were found. Electron microscopy demonstrated two cell types: one with frequent neuritic processes containing neurosecretory granules and showing synaptic specialization, and another one compatible with epithelial adenohypophyseal cells. A few cells had ultrastructural features that were transitional between neuronal cells and granulated epithelial cells. Agranular folliculostellate cells were also identified. Immunoelectron microscopy demonstrated prolactin granules in the cytoplasm of the epithelial cells, in a few transitional cells, and in scattered neuritic processes. Ultrastructural and immunohistochemical features of the tumor suggested a transformation of pituitary epithelium to neuroblastic cells. Hyperprolactinemia and associated clinical symptoms may in part be attributed to selective prolactin secretion by neoplastic cells that were differentiating into adenomatous pituitary cells and, to a lesser extent, to cells differentiating into a neuroblastic line. Compression of pituitary stalk might also have been a contributory factor to the increased prolactin levels. Moreover, the oxytocin produced by the neuroblastic cells was considered an additional stimulus for prolactin secretion by neoplastic cells or by the normal pituitary.

Intrasellar neuronal choristoma associated with growth hormone-producing pituitary adenoma containing amyloid deposits

The histological, immunocytochemical, and ultrastructural features of an intrasellar neuronal choristoma associated with pituitary growth hormone (GH)-producing adenoma are reported. Immunohistochemistry studies and electron microscopy examination showed the adenoma cells to be positive for GH but negative for prolactin, and the neurons of the choristoma to have GH-releasing factor (GRF) neurosecretory activity. The adenoma also had many amyloid deposits in its extracellular space immunoreactive to GRF. This is the first report of the tumor containing amyloid deposits.

Pituitary adenoma with neuronal choristoma (PANCH): composite lesion or lineage infidelity?

Fifteen cases of the rare association of pituitary adenoma and neuronal choristoma (PANCH) were investigated by histology, immunohistochemistry, and electron microscopy. Acromegaly was apparent clinically in 11 patients and was equivocal in 1, and 3 lesions appeared to be nonfunctioning. Histology revealed various proportions of chromophobic PA and nervous tissue consisting of neuronlike cells and neuropil. Immunohistochemistry documented growth hormone (GH) in every PA, including those unassociated with clinical acromegaly. In contrast, the NCH component showed no consistent immunohistochemical profile. Most frequent reactivities were for the pituitary hormone alpha subunit, thyroid-stimulating hormone, and GH, whereas only a few cases displayed scattered positivity for GH-releasing hormone. Low-molecular weight keratin tested positive in PAs and in a few cells and processes of an NCH. A few fibrous bodies were immunoreactive for neurofilament protein. Electron microscopy revealed sparsely granulated GH cell adenoma, neurons, and neuropil. Cells intermediate between PA and neurons were numerous in 1 lesion. The present morphologic findings as well as lack of GH cell hyperplasia and the consistent association of NCH with but one type of PA do not support the causative role of NCH in the initiation of PA, as proposed previously. It appears that NCH is the result of neuronal differentiation within sparsely granulated GH cell adenomas.

Cerebral and cerebellar gangliocytomas: a morphological study of nine cases

Hypothalamic gangliocytomas have been shown to contain immunoreactivity for hypophysiotropic peptides and some have been associated with endocrine dysfunction. Extrahypothalamic gangliocytomas are usually not associated with endocrine abnormalities. We studied nine cerebral or cerebellar gangliocytomas from six men and three women; none of the patients had detectable alterations of endocrine homeostasis. On histological examination, the tumor cells resembled hypothalamic neurons. Electron microscopy disclosed the presence of dense-core vesicles in neuronal cytoplasm and processes resembling Herring bodies, and there were synaptic contacts between tumor cells. All but two tumors contained immunocytochemical positivity for at least one peptide hormone or amine; these included somatostatin, corticotropin-releasing hormone, beta-endorphin, galanin, vasoactive intestinal peptide, calcitonin, serotonin, catecholamines or met-enkephalin. These tumors have been thought to represent neoplasms arising in ectopic autonomic neural tissue. Their morphological features, their similarity to hypothalamic gangliocytomas and the multiple immunoreactivities shown here suggest that they can be regarded as tumors of peptidergic neurons that are widely distributed throughout the central nervous system.

Cushing's disease in a child caused by a corticotropin-releasing hormone-secreting intrasellar gangliocytoma associated with an adrenocorticotropic hormone-secreting pituitary adenoma

Cushing's disease resulting from intrasellar corticotropin-releasing hormone (CRH)-secreting gangliocytomas is very rare, and only two such cases have been reported in the literature to date. The authors present a third case in which an adrenocorticotropic hormone-secreting pituitary adenoma was found in addition to a gangliocytoma in a 10-year-old girl with clinical and endocrinological symptoms of Cushing's disease. Computed tomographic and magnetic resonance imaging scans showed a suprasellar and parasellar tumor. A green-colored, heterogeneous tumor and a small adenoma were removed transsphenoidally. Histological examination revealed a large gangliocytoma immunoreactive for CRH and a small, mucoid cell pituitary adenoma immunoreactive for ACTH. This is the first case of such a tumor causing Cushing's disease in a child. It might exemplify induction of an ACTH-secreting pituitary adenoma by means of chronic overstimulation of CRH.

Use of ultrastructural immunohistochemistry in human pituitary pathology

Recent advances in ultrastructural immunohistochemistry have provided insight into not only the subcellular localization of single antigens but also the colocalization of two distinct antigens in the same cellular constituent. In the field of pituitary pathology, precise identification of cell types, mechanism of processing, and dynamic intracellular transportation of hormones, as well as production of multiple hormones in the same cells of nontumorous and neoplastic adenohypophyses, have been documented by use of these techniques. The present review deals with the use of major methods for ultrastructural immunohistochemistry including pre-, post-, and non-embedding methods, particularly focusing on their application to human pituitary pathology. Problems of tissue processing and a protocol for double labeling technique using the protein A-gold complex are also described.